Case Study in Ordinal Regression, Data Reduction, and Penalization

Abstract

This case study is taken from Harrell et al.¹⁸⁸ which described a World Health Organization study³⁰³ in which vital signs and a large number of clinical signs and symptoms were used to develop a predictive model for an ordinal response. This response consists of laboratory assessments of diagnosis and severity of illness related to pneumonia, meningitis, and sepsis. Much of the modeling strategy given in Chapter 4 was used to develop the model, with additional emphasis on penalized maximum likelihood estimation (Section 9.10). The following laboratory data are used in the response: cerebrospinal fluid (CSF) culture from a lumbar puncture (LP), blood culture (BC), arterial oxygen saturation (SaO ₂, a measure of lung dysfunction), and chest X-ray (CXR). The sample consisted of 4552 infants aged 90 days or less.